Patent Application
20110248495
The present invention relates to a connector, suitable for use with a tubular member such as coiled tubing, and to a method of connecting the connector to a tubular member. Although the invention is described primarily with reference to coiled tubing, other types of tubular member (typically blank ended tubulars) can be used with the connector.
Coiled tubing is used to deploy tools and other items in oil and gas wells. The coiled tubing is a long length of tubing, which is coiled on a reel, and is uncoiled from the reel as it is inserted into the wellbore. The tool or other item to be deployed in the wellbore on the coiled tubing is usually attached to the terminal end of the coiled tubing that is first inserted into the well. Coiled tubing connectors are used for connecting the terminal end of coiled tubing to the tool or other item.
According to the present invention there is provided a connector for connecting to a tubular member, the connector having a body with a bore configured to receive the tubular member, the body having a wedge device within the bore adapted to interact with the body to grip the tubular member when the tubular member is disposed within the bore, wherein the wedge device is at least partially helical, and wherein the connector has an anti-rotation device to restrict relative rotation of the wedge device and the body when the tubular is gripped in the bore.
Optionally the anti-rotation device can act direct on the wedge device, and typically act on the wedge device once it is in a compressed or energised configuration.
In some embodiments, the anti-rotation device can act direct on the tubular to restrict or prevent rotation of the tubular and the wedge device once the wedge device is energise by the movement of the tubular.
The wedge device can be in the form of a helix having more than one turn, or can be a single turn helix.
The wedge device can be any device that is tapered, typically on its outer surface, and which typically interacts with a matching tapered surface on the inner surface of the bore of the body, creating a wedging effect on the tubular to restrain it within the bore of the body, and typically acting to restrict or prevent axial movement of the tubular. The inner surface of the wedging device is typically configured to match and optionally to grip the outer surface of the tubular. The wedge device is designed to move within the bore with the tubular, and to exert a compressive force on the tubular within the bore to make up the connector.
The wedge device can interact with a seat in the body, which guides the movement of the wedge device in order to apply the compressive force against the tubular. The seat can also be in the form of a helix.
The seat can have tapered side walls acting to radially compress the wedge device against the tubular member when the tubular member moves axially in one direction within the bore, and to reduce radial compression on the tubular member when the tubular member moves axially within the bore in the other direction. In some embodiments, the seat can radially compress the wedge device when the wedge device and the seat rotate relative to one another in one direction, and can optionally reduce radial compression on the wedge device when the two are rotated relative to one another in the opposite direction.
According to the present invention there is provided a method of connecting a connector to a tubular member, the connector having a body with a bore configured to receive the tubular member, and having a partially helical wedge device within the bore, the method comprising gripping the tubular member within the bore, and locking the body and wedge device against rotation relative to one another when the tubular is gripped in the bore. In one embodiment, the wedge device is rotated relative to the body before being locked against relative rotation between the two.
In one embodiment the wedge device is pulled axially relative to the body before being locked against relative rotation between the two.
Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Referring now to the drawings,
The wedge member 10 is typically in the form of a resilient steel strip that is coiled into an anticlockwise helix, as shown in
Below the seat 6, at the lower end of the body 51, the bore 7 narrows to form a locking section 20 in the body 5, which has O-ring seals 18 located in annular recesses 19 to seal the coiled tubing 15 within the body 5. Below the locking section 20, a box or pin connector is provided for attachment to a tool (not shown) below the connector. The box or pin connector can be of any suitable design, and is typically chosen to cooperate with whichever component the tubing is to be made up to. The box or pin connector can optionally have a fluid channel to communicate with the bore 7, in order to allow fluid communication with the bore of the coiled tubing 15. In some embodiments, this will not be necessary. Typically the body 5 is formed as a single piece and the bore 7 is counter-bored from the apertured end. In certain embodiments, the body can be formed from a number of interconnected portions.
The locking section has a number of radial holes 22 drilled and tapped to receive threaded fixings such as bolts or screws 23. The bolts 23 are typically socket headed and are optionally threaded through the wall of the body 5 and can be driven against the coiled tubing 15 once in place in the bore 7 of the locking section 20.
Typically the wedge member 10 has three or more coils in the helix, but the number of coils in the wedge device can be varied. The helical wedge member 10 has a radially inner surface and a radially outer surface, and an axial bore 10b. In some embodiments the inner surface of the wedge member 10 that engages the outer surface of the coiled tubing 15 can be smooth, but the wedge member 10 can optionally grip the coiled tubing 15 more effectively if the inner surface has a profile like a wicker thread or a screw thread to increase the grip. The inner surface of the wedge member 10 can optionally be hardened. The radially inner surface therefore optionally has a wicker thread with radial projections, typically in the form of a helical thread 10s with saw-toothed cross sections, which extend the length of the wedge member 10. Typically three or four turns of thread 10s extend from the inner surface of each coil of the helical wedge member 10. In this example, the pitch of the thread 10s and the pitch of the helical wedge member 10 are the same, but this is not essential, and the pitch can be varied, and/or a finer or coarser thread can be provided in other embodiments.
The thread typically has an inclined face and a generally radial face. The inclined face is typically above the radial face i.e. closer to the aperture at the end of the bore 7. The radial face is aligned more closely with the radius of the wedge member 10 than the inclined face, which is more aligned with the long axis of the bore, but which inclines outwardly toward the top of the step. The generally radial face does not need to be precisely radial. The radial face and the inclined face meet at the radially innermost apex of each tooth. It will be appreciated that the particular angles of the two faces can be varied.
The thread engages the outer surface of the coiled tubing, and typically increases the grip of the wedge member 10 on the coiled tubing 15 held within the wedge member 10. In this example, the thread is not symmetrical, and allows the wedge member 10 to move up the coiled tubing more easily than it can move down the tubing. Therefore, the resistance to axial movement that is applied to the coiled tubing 15 by the wedge member 10 is greater in one direction (up, in the drawings) than in the other (down, in the drawings).
The outer surface of the wedge member 10 has an axial face 10a and a tapered face 10i. The axial face 10a is aligned with the axis of the bore 7. The tapered face 10i is arranged above the axial face 10a and is inclined slightly toward the top of the wedge device at an angle of around 5-20 degrees (e.g. 10-15 degrees) to the vertical.
The seat 6 has a profile that matches the outer surface of the wedge member 10. In particular, the seat 6 is in the form of a helix and describes a continuous helical path on the inner surface of the body 5, although in certain embodiments, the path could be non-continuous. In this embodiment, the seat has a continuous helical shoulder 61 extending radially into the bore 7 at approx 90 degrees to the axis of the bore 7, from the aperture at the top 5u of the body to the commencement of the narrowing at the locking section 20. The shoulder 61 is generally radial. The side faces 6i of the seat 6 are tapered or inclined between the adjacent coils of the ledge 61 to match the incline of the outer surface of the wedge member 10. This creates a wedge effect between the inner surface of the seat 6 and the outer surface of the wedge member 10. Therefore, movement of the helical wedge member 10 up the bore 7 causes radial compression of the wedge member 10 by virtue of the inclination of the faces 10i and 6i.
In use, the body 5 is equipped with O-rings on the surface, and the helical wedge member 10 is offered up to the aperture 5a at the end of the bore 7 and is threaded into the bore 7 from that end while being rotated, engaging and being guided down the bore 7 by the matching helical seat 6. The bore 7 of the body is co-axial with the bore 10b of the wedge member 10.
Once the wedge member 10 has been fully received within the helical seat 6, the connector is in the configuration shown in
The lower end of the locking section 20 has an annular shoulder 20s that is narrower than the diameter of the coiled tubing 15. Once the coiled tubing 15 has bottomed out on the shoulder 20s, it can move no further into the bore 7, and is now in the position shown in
The tubing 15 can then be pull-tested to further energise the wedge member 10, and to test the make up of the connector 1. This relative movement of the coiled tubing 15 and the wedge member 10 carries the wedge member axially with the coiled tubing up the bore toward the aperture 5a, because of the wicker thread profile that holds the wedge member 10 onto the outer surface of the coiled tubing.
The wedge member 10 therefore moves up the seat 6, and the interaction between the inclined faces 10i and 6i push the wedge member 10 inward and cause the wedge member 10 to bite into the outer surface of the coiled tubing, therefore locking the coiled tubing and the wedge member securely together, and leaving the connector and the coiled tubing 15 in the configuration shown in
Once the tubing 15 no longer moves from the position shown in
In the present embodiment, the anti-rotation device(s) engage the tubing 15, which remains locked onto the wedge member 10 by means of the grip applied by the compression of the wedge member 10 within the bore 7. However, in certain other embodiments, the anti-rotation devices can engage the wedge device directly, and prevent its uncoiling within the bore, and do not need to engage the tubing direct.
Instead of the screw-threaded fixing, alternative designs of anti-rotation devices can be employed, such as pins, bars or circlips, configured to prevent or restrict uncoiling of the wedge device from its energised helical configuration. One advantage of this arrangement is that relatively weak pins can be provided spaced helically along the length of the helical portion of the wedge device in order to restrain its tendency to uncoil and lose its grip on the tubing.
Thus certain embodiments of the invention allow the attachment of tools to the bottom of a tubular member without the need to cut threads, crimp or deform the tubular in order to positively attach the tools. Also, certain embodiments can reduce the size and length limitations of existing designs of connector, and can facilitate making up the connectors onto coiled tubing with any residual bend. Some embodiments allow faster make up of the connector, and can reduce handling time and exposure to risks as a result, without sacrificing connection strength.
Referring now to
Note that the bolts do not need to withstand axial loads, and only need to restrict rotation. The bolts do not need to have a screw thread, and simple pins can be used instead, in some embodiments. Thus a simple pair of pins provided connecting the body and the wedge member at the upper and lower ends of the wedge member could suffice to restrict rotation of the wedge member. Note that this embodiment has anti-rotation devices that act directly on the wedge member, but it is possible to construct embodiments of the invention in which the anti-rotation device does not bear directly on the wedge member but restricts its rotation indirectly, via another component, such as the tubular.
Referring now to
The inner diameter of the anti-rotation slip 83 optionally has a gripping pattern that can optionally be hardened. In this example the gripping pattern can be parallel serrations which run axially along the component thereby restricting rotational movement of the tubular relative to the body 65 when the collar 82 is securely connected at the thread 82s. Alternative designs of gripping pattern can include diamond patterns. The gripping pattern can be cut into the inner surface of the slip 83, or can extend radially inwards from it. It can be regular or irregular. Locking bolts or other fixings could optionally be included to a) prevent the thread from backing off and b) to prevent the anti-rotation slip rotating in relation to the taper sub.
Modifications and improvements can be incorporated without departing from the scope of the invention. For example, the helix can be a right hand or a left hand helix. The connector is shown attached to the bottom of a coiled tubing string, but could also be attached to other sectors of the string, for example, in the middle or at the top of the string, or can be used to interconnect two tubing strings.
